A geometric construction of topological invariants for crystals with time-reversal symmetry

Condensed Matter seminars

Wednesday 13 September 2017
from 15:30
to 16:30at
Nordita South

Speaker :

Krzysztof Gawedzki (ENS de Lyon)

Abstract :

I shall discuss a construction of Z_2-valued invariants of topological phases for 2d and 3d time-reversal symmetric crystals, both static and periodically driven. The construction uses a geometric structure (a gerbe) on U(N) that encodes ambiguities of the logarithm of a unitary matrix.